Re: [PATCH 1/2] wifi: mac80211: use aesgcm library

[Eric Biggers <ebiggers@kernel.org>]

Hi Johannes,

On Tue, May 05, 2026 at 11:18:38PM +0200, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> Instead of dynamically allocating the gcm(aes) algorithm, use
> the library. This is faster and avoids the extra allocation.
> 
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
> ---
>  net/mac80211/Kconfig   |  2 +-
>  net/mac80211/aes_gcm.h | 39 +++++++++++++++++----------------------
>  net/mac80211/key.c     | 11 +++--------
>  net/mac80211/key.h     |  3 ++-
>  net/mac80211/wpa.c     |  9 +++++----
>  5 files changed, 28 insertions(+), 36 deletions(-)

I really appreciate the enthusiasm for the crypto library!  And it isn't
surprising, since it's clearly the way to go.  But I do think these two
patches are jumping the gun a bit, since we haven't yet migrated all the
optimized AES-GCM code into the library, or added an improved AES-GCM
API that provides enough functionality to fulfill all the in-kernel use
cases (for example, incremental computation of AES-GMAC).

So as-is these two patches could regress performance in some cases
(despite the library having less overhead).  And also the AES-GCM API is
likely to change a bit.  In particular I don't think code outside the
crypto subsystem should be constructing its own AES-GMAC by combining
the GHASH functions with the AES functions, as your second patch does.
Instead they should invoke an AES-GMAC API (or AES-GCM, of which
AES-GMAC is a special case) provided by lib/crypto/.

So I'd ask that we wait just a bit until I can finish getting the
AES-GCM library APIs into a good state.  I got a lot of the prerequisite
work in for 7.0 and 7.1, and I'll see if I can finish it in 7.2.  I've
just been a bit busy with other things in the past few weeks.

Thanks,

- Eric